Add distclean in Makefile and CPPFLAGS defaults

Makefile

@@ -1,11 +1,11 @@
 CXX ?= c++
-CPPFLAGS ?=	-Wall 				\
+CPPFLAGS ?= -O2
-		-Wextra				\
+CPPFLAGS += -Wall 			\
-		-pipe				\
+	    -Wextra			\
-		-Wmissing-declarations		\
+	    -pipe			\
-		-pedantic			\
+	    -Wmissing-declarations	\
-		-fstack-protector-strong	\
+	    -pedantic			\
-		-O2
+	    -fstack-protector-strong	\
 	
 LDFLAGS=-lncursesw -Wl,-z,relro,-z,now
 
@@ -32,5 +32,7 @@ $(EXECUTABLE): $(OBJECTS)
 	@$(CXX) $(CPPFLAGS) -c $< -o $@
 
 clean:
-	rm -rf $(OBJECTS)
+	rm -rf $(OBJECTS) $(EXECUTABLE)
 
+distclean:
+	rm -rf $(OBJECTS)